An ad valorem tax on demanders causes the _____ to shift by a constant _____

When a negative externality is present in a market, when a tax is imposed, it is:

A. inefficient, because the net benefit of buying another unit is zero for all market participants. B. efficient, because the government mandates the efficient quantity without regard for net benefits. C. inefficient, because the government mandates the efficient quantity without regard for net benefits. D. efficient, because the net benefit of buying another unit is zero for all market participants.

Other things being equal, a higher price induces

A. buyers to reduce the amount they want to buy and sellers to reduce the amount they are willing to sell. B. buyers to increase the amount they want to buy and sellers to increase the amount they are willing to sell. C. buyers to increase the amount they want to buy and sellers to reduce the amount they are willing to sell. D. buyers to reduce the amount they want to buy and sellers to increase the amount they are willing to sell.